Historically, grease traps have been used in restaurants and other commercial facilities to limit the amount of grease and solid waste that it carried into sewer systems via waste water. Typical grease trap are either passive grease traps or automatic grease traps. Passive grease traps are usually only emptied of the waste periodically and therefore waste tends to build up inside the tank. Passive grease traps typically include a tank with an inlet that brings in waste water and an outlet that carries water out of the system. Lightweight grease rises to the top of the tank and heavier solids settle in the bottom of the tank. A problem with many grease traps is that water may flush through the system with such velocity that it disrupts the grease that has already separated, causing the waste to be expelled with grey water. This is especially true as the tank fills up with grease, so that the grease/water interface is closer to the grease trap bottom.
As such, present grease traps, though effective to remove some grease and solid waste from solids containing liquids, do not adequately prevent grease from going downstream with the water. Thus there remains a need for a low cost, more effective grease trap for removing solids and grease from wastewater.